Goods Service Tax Calculator
GST / VAT Calculator works out Tax amount and Tax-inclusive total from Amount, Tax rate and Direction. The default figures on this page give tax-inclusive total of 118; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- Tax = amount x rate / 100 = 100 x 18 / 100 = 18
- Total = amount + tax = 100 + 18 = 118
- Tax at 18% = 18
Tax headstable
| head | ratePercent | amount |
|---|---|---|
| Tax | 18 | 18 |
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
4 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the GST / VAT Calculator calculates
Adds a goods and services tax to a net amount, or extracts the tax already contained in a gross amount, and splits it into CGST/SGST or IGST heads where required.
How to use this GST / VAT Calculator
Enter Amount, Tax rate, Direction and Component split. Tax amount updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Tax amount, Tax-inclusive total and Tax-exclusive net.
The method follows Central Board of Indirect Taxes and Customs, GST rate structure (5%, 12%, 18%, 28%) and CGST/SGST/IGST heads, Canada Revenue Agency, GST/HST rates by province and territory, Australian Taxation Office, GST is 10% of the price of most goods and services and Inland Revenue New Zealand, GST rate of 15%.
100 at 20% (research case R4019-GT-1) example
With Amount: 100, Tax rate: 20, the calculator returns Tax amount: 20, Tax-inclusive total: 120. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Tax amount, Tax-inclusive total and Tax-exclusive net. The inputs you can vary are Amount, Tax rate, Direction, Component split and Quantity.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I calculate my GST?
Adds a goods and services tax to a net amount, or extracts the tax already contained in a gross amount, and splits it into CGST/SGST or IGST heads where required. Open “How this is worked out” beside the result to see each step for your own figures.
How to add 8.25% sales tax?
It needs Amount, Tax rate, Direction, Component split and Quantity. Nothing else is required, and the figures stay in your browser.
How do I calculate GST from a total?
The result gives Tax amount, Tax-inclusive total, Tax-exclusive net, Rate applied, Tax as a share of the gross and Tax heads, each labelled with its unit so the figure can be read on its own.
How much GST will I pay on $600?
On the figures this page opens with — amount 100 and tax rate 20% — the tax-inclusive total is 118. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the GST / VAT Calculator?
You need Amount, Tax rate, Direction, Component split and Quantity. The page opens with default figures that give tax-inclusive total of 118, so you can see the scale before entering your own.
What does this GST / VAT Calculator show?
It shows Tax amount, Tax-inclusive total, Tax-exclusive net, Rate applied, Tax as a share of the gross and Tax heads, with the working and any warnings for your entries.